Sedimentological and mineralogical study of a coastal deposit of Balos’s ravine. Gran Canaria. Canary Islands

Abstract

Stratigraphic, sedimentological and mineralogical study of a stratified coastlike deposit, nestled on the South slope of the Balos’s ravine, was performed by the examination of thin sections from the sediment samples collected throught the Balos column. This sedimentary body was firstly cartographied in the Magna geological map of Ingenio as an alluvial fan deposit, stratigraphically dated as Miocene (about 14 Ma). Applying the mineralogical and sedimentological results it has been possible to contribute with clues to interpret this deposit, for instance, the identification of the source material (basaltic and tracy-rhiolitic Formations from the Shield Stage of the Island), it low angle and the relative fine sediment (mainly sandy-silty grain size); all this could indicate that this outcrop represent the distal part of a fan delta. By the other hand, the normal sequence grading of the deposit (the upwards grain size decressing) could reflect the retrogradation of this fan delta, explained, perhaps, with a marine transgression event. The presence of quartz in this deposit might evidence the eolic dust arrivals from a Saharan desert at this age (c.a. 14 Ma)